This invention relates to wireless transmission and reception, and more particularly to transmitters and corresponding receivers that are characterized by extremely low average power consumption but which, nevertheless, possess high selectivity.
Numerous objects have nowadays become an integral part of almost everybody's life. Aside from keys, wallet and purses, which have been common for years, many people now carry a cellphone, and often other electronic appliances. A lost cellphone represents a significant loss both because much functionality is included into the cellphone, and because the cost of a replacement phone is quite high. Alas, it is the nature of oft-used small portable objects that they are casually put aside and, consequently, the user sometimes forgets to take the object along as the user walks away, or forgets where the user put down the object. Consequently the “misplaced” object is either found after some effort and associated consternation, or is truly lost. Also, unfortunately, sometimes such objects are actually stolen.
It would be beneficial to overcome this problem with, for example, a low cost, low power consumption, miniature size, proximity sensor that alarms a user that his/her electronic appliance or other valuable (such as luggage, wallet, purse etc.) is left behind.
Therefore, it is a primary objective of this invention to alert a user within a reasonable time when an object that is normally in close physical proximity of the user is outside an expected proximity of the user.
Another objective of this invention is that whatever is done to the object, such as to modify it or to attach something to it encumbers the object in a de minimis manner.
Still another objective is for provide a solution that presents an extremely low current drain on whatever supplies the operating power to the device that achieves the primary objective.
Yet another objective is to make it unlikely that an alert would be erroneously sounded, such as resulting from interferences by other devices.
Furthermore, it is an objective to create a system where more than one object can be tracked by a single device.